The body in cold weather

27 °C (80 °F) IS IDEAL
Man is a tropical animal who has adapted over thousands of years to be comfortable without clothing at 27 °C (80 °F). At this temperature, the body works optimally, and maintains a steady internal temperature of 37 °C (98.6 °F).

In order for our bodies to work properly, we need to provide energy in the form of food and water. This enables our hearts to pump, our muscles to work, and our brains to function. Approximately 70% of that energy is needed to maintain a constant core temperature.

THE BODY’S HEAT PRODUCTION
Body heat is created by burning food, such as fat, carbohydrates and protein. Heat is produced mainly in the muscles, and increases the more work the muscles do. In a cold environment, the body needs external help to maintain its temperature. We have to add extra energy by drinking and eating more, we need to dress right, and we need to keep active in order to avoid getting cold.

At rest, our bodies’ normal heat production is roughly 80 to 100 Watts – the equivalent output of a normal light bulb. During intense physical work, the body can put out 1000 Watts.

WHEN THE BODY GETS COLD
When the body gets cold it tries to create heat by shivering. The body can increase its own heat production 4-5 times by shivering. The body also decreases blood flow to the hands and feet in order to prioritize heat to the heart, brain and other vital organs, which is why you first feel cold in your hands and feet even though the rest of your body feels warm.

TO PERSPIRE
To perspire is a normal reaction when the body is too hot and needs to cool down the skin. The skin cools
because the moisture – sweat – evaporates. This functions very well in a hot climate, but in cold weather, when you are wearing lots of clothes, heavy sweating can prove disastrous when the moisture will actually make you colder.

0.5 to 1 liter of fluid evaporates from the skin every day. During hard work, the evaporation can reach several liters per hour.

AT 58 °C (-72 °F) BELOW ZERO. While the Swedish explorers Mikael Strandberg and Johan Ivarsson traveled along the Kolyma River in Siberia, temperatures plunged to -58 °C (-72 °F). They were able to handle the extreme cold thanks largely to Woolpower® garments.